Balance-valve



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j. APatented Fem-15,1881.

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IIIIII llllllll IIII NiTE' Str-.atras JOHhT H. GREENWOOD, OF COLUMBUS, OHIO.

BA LAN C EA-VALVE.

SPECIFICATION forming part of Letters Patent No. 237,742, dated February 15, 1,881.

Application filed September 21, 1880. (Model.)

To all whom .it may concern Be it known that I, JOHN H. GREENWOOD, of Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Seats for Balance- Valves; and I do hereby declare that the followingis a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form apart of this specication.

Figure l is a plan of the valve-seat; Fig. 2 is a transverse vertical section of the valve and seat. Fig. 3 Ais a perspective view of the valve and seat, the valve being partly in section.

The same letter indicates the same part wherever it occurs in the figures.

The nature of my invention consists in providing the valve-seat and bridges of a slidevalve with a number of rows of holes or slots opening under the valve and connected with the steam-chest, so as to take steam directly from it, and so controlled by the movements ofthe slide-valve that the pressure upon the valve shall be relieved by counter pressure in every position, while the steam is never allowed to blow through the holes into the eX- haust, all as hereinafter more particularly set forth.

In the drawings. the valve-seat is represented as having four longitudinal rows of holes, `A B B' A', and two transverse rows, F F' J J'. The longitudinal rows A A', communicate at all times directly with the steamchest by means ot' the lateral rows of holes which open into them from the chest, as shown in Fig. 3, and at F F' in Fig. 2. The' holes 3 4 5 6 7 ot' the transverse rows are also open to the steam-chest inthe same way. The rows B B' are on the bridges G G', respectively. The holes in each of these rows are laterally connected with each other, as shown by dotted lines, and when either row is covered by the lip lof the valves C, that row communicates with the steam-chest and takes steam only through the hole l or 2, as the case may be. The holes 1 and 2 do not communicate by lateral holes with the steam-chest.

I) D' mark the steamways; E, the exhaust;

G G', the bridges, and H H' the sides of the valve-seat. l Z' mark the lips of the valve.

Such being the construction, the operation is as follows: When the valve is in the position shown in full lines in Fig. 2 the lip Z' is over the row of holes A' A' on the margin H' of the valve-seat, and the lip l is on the bridge G, over the row of holes marked B B. The row A', taking steam directly from the lateral holes connected with them, counteracts or balances the pressure on lip Z', and the row B, taking steam through holes 1, balances the pressure on lip l, while row B' is shut o from communication with the steam-chest by reason of the holes 2 being covered by the lip ot' the valve, and steam is thus prevented from blowing through into the exhaust. When the valve O is iu the position shown in dotted lines in Fig. 2 the lip l' is on bridge Gandover the row of holes B', which takes steam through holes 2, which are then uncovered. Lip Zis over the row A, and row B is prevented from allowing steam to blow through from the steam-chest to the exhaust, by reason of holes 1 being covered by the lips ot' the valve. The pressure on the end margins of the valve is relieved by the holes 3, 4, 5, 6, and 7 on line-s F F' and J J which are always Open to the steam-chest. TheV size of the holes will depend upon that ofthe valve and the construction ot' the bridge-walls. The holes are kept free from dust and greaseby the steam blowing through them (when they are uncovered) as it passes from the steam-chest to the cylinder.

l am aware that open V-shaped grooves cut in the face of the valve-seat have been used in combination with recesses in the bearing-surface of the valve, for a purpose similar to that which I accomplish. This construction I do not claim. I think it would tend to increase friction and soon become so clogged with grease and dirt as to be practically inoperative.

What I claim, and desire to secure by Letters Patent, is

l. A valve-seat for balance-valves in which rows of holes are made and connected with the steam-chest in the manner described, so as IOO 4. The arrangement and location oftheholes l l and 2 2 relatively to the rows of holes B and B', and the lips l l of the slide-valve C, in 15 the manner described, for the purpose set forth. In testimony that I cla-im the foregoing as my own invention I affix my signature in presl ence of two Witnesses.

JOHN H. GREENWOOD.

2. A Valvesent for balance-valves in which the bridges G G are provided with holes oonneeted with the steam-chest, to relieve the pressure of the valve upon the bridges without permitting the escape of steam through the bridges from the steam-chest to the exhaust, all in the manner speeitied.

3. The combination, in @balance-valve seat, of the rows of holes A B B A F F J Jf, constructed and arranged as described, with a steam-chest and slide-valve, all operating in the manner and for the purpose specified.

Witnesses:

E. Tnos. HUGHES, IRA A. HUfromNsoN. 

